| Dissolved and particulate lipid extracts were collected at a number of locations in the Gulf of Mexico, the Scotia Sea, and in and near the Cariaco Trench. Lipid material was defined as those organic compounds extractable with chloroform. The lipids of sea water were a very complex mixture of compounds. Lipids constituted (TURN)4% of the dissolved organic carbon and (TURN)20% of the particulate organic carbon. All concentrations of lipids measured were extremely low and apparently of biogenic origin. Lipid content was estimated both gravimetrically and gas chromatographically. Compounds in the extracts were identified by a combination of authentic standards, gas chromatography-mass spectrometry, and high resolution mass spectrometry. The major constituents (10-100 ng/l) of the analyzable dissolved lipids were n-alkanes, pristane, phytane, and alkyl esters of fatty acids. Minor components ((LESSTHEQ) 5 ng/l) included olefins and/or cycloalkanes, an indane, a few aromatics, short-chained acids, and possibly a lactone and an alcohol. The major constituents of the analyzable particulate lipids were also n-alkanes, pristane, phytane, and the alkyl fatty acid esters. Often olefins, alkylated benzenes, quinones, and the unresolved G.C. material were significant components of the particulate lipids. Minor components of the particulate lipids included ketones, phenols, an indane, benzoates, aromatics, and possibly derivatives of inositol, dioxane, and pyran. Both phases had compounds that were unique and many compounds that were similar.;N-alkanes may have two sources (marine and terrestrial) superimposed on a low fairly constant background of hydrocarbons caused by low level chronic oil pollution in the Gulf of Mexico. Fatty acid alkyl esters may be the product of the degradation of humic substances and glycerides; as such their distribution may indicate rates of degradation and the stability of the organic matter present in aquatic environments. Indanes, phenols, benzoates, and other compounds detected in this study may prove to be useful indicators of source.;Lipids of temperate climates (Gulf of Mexico) and polar climates (Scotia Sea) had similar gravimetric concentrations and similar dominant compounds. The fractionated lipids had different distributions for the two locations. The Scotia Sea samples gave generally simple G.C. patterns which reflected a mainly marine source for lipids. Lipid content appeared to be lower in the pack ice as compared with open ocean values. An island effect was demonstrated in the n-alkane distributions.;The complexity of natural organic mixtures make their analysis difficult if not impossible. Added to this problem are the extremely low values encountered and the concurrent problem of contamination during collection and processing of samples. A number of trends and new compounds have been identified in this study. More extensive sampling, more laboratory studies, and the application of the latest analytical techniques to the study of organic matter in aquatic environments will be necessary to understand the cycling and interactions of organic matter.;Seasonal, diurnal, vertical, and areal variations were observed in lipid content. The dissolved lipids were less variable than the particulate lipids. The lipid content of particulate organic carbon decreased with depth. Lipid concentrations reflected variations in routine oceanographic parameters such as salinity and temperature and the aperiodicity of sources. Anoxic conditions appeared to preserve lipid materials in the particulate phase. |
